User Guide

Contents

Control Collection with an MPI_Pcontrol Function

By default,
Intel® Advisor
analyzes performance of a whole application. In some cases, you may want to focus on the most time-consuming section or disable collection for the initialization or finalization phases. This can decrease collection overhead.
Intel Advisor
supports the MPI region control with the
MPI_Pcontrol()
function. This function allows you to enable and disable collection for specific application regions in the source code. The region control affects only MPI and OpenMP* metrics, while other metrics are collected for the entire application.
To use the function, add it to your application source code as follows:
  • To pause data collection, add
    MPI_Pcontrol(0)
    before
    the code region that you want to disable the collection for.
  • To resume data collection, add
    MPI_Pcontrol(1)
    where you want the collection to start again.
  • To skip the initialization phase:
    1. Add the
      MPI_Pcontrol(1)
      function right after initialization.
    2. Build the application.
    3. Run Intel Advisor analyses with the option. For example, to run the Survey analysis:
      advisor --collect=survey --start-paused --project-dir=./advi_results -- ./mpi_sample
Intel Advisor
accepts only 0 and 1 arguments for the
MPI_Pcontrol()
function. You can use other numbers to mark code regions, but
Intel Advisor
ignores them.
For code snippet examples, see Region Control with MPI_Pcontrol.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.